JPH02248086A - Acceleration sensor - Google Patents

Abstract

PURPOSE:To enhance an acceleration sensor of this design in voltage sensitivity so as to improve it in S-N ratio by a method wherein the back electrode of a piezoelectric element is divided into two pieces, and a lead wire is connected to each of the pieces. CONSTITUTION:A back electrode 2 of a piezoelectric vibrator 1 which constitutes an acceleration sensor is divided into two, and a lead wire 3 is connected to each of the discrete electrodes so as to double voltage sensitivity to improve the acceleration sensor in S-N ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an acceleration sensor used for general vibration detection and acceleration measurement.

2. Description of the Related Art Conventionally, this type of acceleration sensor has had a configuration as shown in FIGS. 3 and 4. In the figure, electrodes 2 are provided entirely on the front and back surfaces of a chip-shaped piezoelectric element 1. This piezoelectric element 1 is inserted between two lead wires 3 with an inclination of 30 degrees, and in this state, the lead wires 3 and the electrodes 2 of the piezoelectric element 1 are fixed with solder 4, and this fixed part is bonded with epoxy. Reinforced with agent 5. Note that 6 is vacuum sealed and piezoelectric element 1
This is a case to protect.

In the acceleration sensor configured in this way, when an external vibration is applied in the vertical direction, the piezoelectric element 1 senses the vibration, causes a deflection according to the magnitude of the external vibration, and uses the piezoelectric effect to respond to the magnitude of the deflection. generates an electric charge. The output voltage is taken out through the lead wire 3.

Problems to be Solved by the Invention In such a conventional configuration, the output voltage generated by external vibration is about 9 mVo-p per 1 G, and when the acceleration becomes low, the S/N ratio decreases to 0. There was a problem in that it was impossible to measure accelerations below IG. It is also conceivable to increase the length of the vibrator in order to increase the sensitivity, but this is not suitable for miniaturization. Further, the structure in which the piezoelectric element 1 is inclined at 30 degrees with respect to the lead wire 3 requires a complicated manufacturing method and increases manufacturing costs.

The present invention solves these problems by increasing the sensitivity and improving the S and N ratios at low accelerations.
Furthermore, supplying an acceleration sensor with a simple manufacturing method,
The purpose is to

Means for Solving the Problem In order to solve this problem, the present invention divides the electrode on the back surface of the piezoelectric element and connects a lead wire to the divided electrode.

Operation With this configuration, when external vibrations are applied, the cantilever-shaped piezoelectric element senses the vibrations, thereby generating a charge in each partial electrode. These charges are combined because the surface electrode of the piezoelectric element is a full-surface electrode, and when the back electrode is divided into two, it is combined.
Since twice the output can be obtained, the S/N ratio is improved.

Furthermore, since the piezoelectric element is attached parallel to the lead wire, the manufacturing method is extremely easy.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 and 2.

In the figure, electrodes 2 are provided on the front and back surfaces of a piezoelectric element 1, and the electrode on the back surface is divided into two from the center. The divided electrodes on the back side are attached parallel to the two lead wires 3 and fixed with solder 4, and the fixed part is further reinforced with epoxy resin 5, and in this state, it is vacuum-sealed inside the case θ. has been done.

When external vibration is applied in the vertical direction to the acceleration sensor configured in this way, the cantilever-shaped piezoelectric element 1 senses the vibration and movement, and deflects according to the magnitude of the external vibration due to the piezoelectric effect. A charge corresponding to the size of the charge is generated, and an output voltage is output through the lead wire 3.

Effects of the Invention As described above, according to the present invention, the electrode on the back surface of the piezoelectric element is divided and a lead wire is connected to each divided electrode, so the voltage sensitivity can be increased several times, and the S/N ratio can be increased. improves. Furthermore, since the piezoelectric element is connected in parallel to the lead wire, the manufacturing method becomes extremely easy and mass productivity is improved.

[Brief explanation of drawings]

FIGS. 1a and 1b are a side sectional view and a front sectional view showing an acceleration sensor according to an embodiment of the present invention, and FIGS. 2a and 2b are sectional views, respectively. C is a plan view and a front view of the piezoelectric element of the same acceleration sensor. Figures 3a and 3b are a side sectional view and a front sectional view showing a conventional acceleration sensor, and Figures 4a, b, and c are a top view, front view, and back view of the piezoelectric element of the same acceleration sensor. . 1... Piezoelectric vibrator, 2... Electrode, 3...
・Group/Lead line, 4...Solder, 6...
Epoxy resin, 6...case. Name of agent: Patent attorney Shigetaka Awano and one other person (Q
) (b 6111 case Fig. 2

Claims (1)

[Claims] The acceleration sensor comprises a case and a piezoelectric element provided in the case, electrodes are provided on the front and back surfaces of the piezoelectric element, and the electrode on the back side is divided, and a lead wire is connected to each divided electrode on the back side. sensor.